The present invention relates generally to cartridges for computer printers. More specifically, the invention relates to a protective cover for an organic photoconductor (OPC) and a mechanism for uncovering the OPC when it is installed for use in a printer.
Conventional laser printers utilize one or more printer cartridges 10 that comprise an organic photoconductor roller (OPC) 12, with exposed photoconductor surface 13, as well as mechanisms necessary to produce a developed image on the OPC for transfer to paper or to an intermediate transfer belt 14. A cartridge with these mechanisms is shown schematically in FIG. 1. These cartridge mechanisms are known in the art and include a charge roller 16, a window 18 from the outside surface of the cartridge to the OPC for laser writing of a latent image on the OPC, a fresh toner reservoir or xe2x80x9chopperxe2x80x9d 20, a system 22 for metering toner and applying it to the OPC to develop the latent image, and a waste toner removal mechanism and waste toner hopper 24.
Because the printer cartridge includes an OPC, which is vulnerable to damage by light, dust, or grime, the typical printer cartridge 10xe2x80x2 includes a movable cover 11 that lies substantially over the surface (13) of the OPC 12 that extends from the cartridge housing whenever the cartridge is removed from the printer. See FIG. 2. Two rigid wire arms 15, 15xe2x80x2 extend out from the cartridge cover 11 at each end of the cartridge 10xe2x80x2. The cartridge is installed into a cavity inside the printer, by moving the cartridge in a direction perpendicular to the longitudinal axis of the cartridge. As the cartridge enters the cavity, the xe2x80x9celbowsxe2x80x9d 17 of the two wire arms abut against shoulder surfaces in the walls forming the cavity and are thereby forced to pivot in a direction that flips the cover angularly away from the OPC to uncover the OPC. Thus, during use, the OPC is uncovered and in contact with the transfer station to transfer developed images to paper. When the conventional printer cartridge is removed from the printer, it is pulled out of the cavity, which allows the spring-biased cover to rotate to cover the OPC.
Still, there is a need for an improved printed cartridge with an improved cover for the OPC. There is a need for a cartridge that can be reliable and accurately placed inside a printer, with an OPC cover that smoothly and reliably moves out of the way for cartridge use, and moves again into place to protect the OPC upon cartridge removal.
The present invention is a mechanism for uncovering the organic photoconductor of a printer cartridge when the cartridge is installed inside the printer. The mechanism comprises a movable cover or xe2x80x9cshutterxe2x80x9d shaped to extend over the otherwise-exposed exposed OPC surface, and a mechanism to move the shutter relative to the OPC, powered by the force of inserting the cartridge into the printer. The mechanism may comprise a cooperating protrusion and ramped recession, wherein the xe2x80x9crampingxe2x80x9d is oriented in a direction that slides the protrusion to the desired position. Preferably, the protrusion extends from the shutter, and the recession is in a surface of the printer cavity that guides the shutter to open when the cartridge is being moved into the printer. Alternatively, the protrusion may extend from the cavity surface and the ramped recess may be located on the exterior of the shutter.
Preferably, a tab extending out from the shutter is received in a slot in an inside printer surface and slides along the slot during cartridge insertion. The slot is slanted or xe2x80x9crampedxe2x80x9d relative to the direction of travel of the cartridge so the tab, retained in the slot, applies force on the shutter to move it away from the OPC. Thus, insertion of the cartridge causes the shutter to open and reveal the OPC. In reverse, removal of the cartridge causes or allows the tab to again slide along the slot, but in a reverse direction from the insertion direction, closing the shutter to cover the OPC.
The shutter opening mechanism and closing mechanism may therefore be entirely actuated by the movement of the cartridge into and out of the printer, and may require no other power source. Alternatively, spring-biasing may be added to assist in smooth and non-jamming movement.
Preferably, the invented mechanism is utilized on a printer cartridge that is adapted to slide longitudinally into the printer. By xe2x80x9clongitudinallyxe2x80x9d is meant the direction parallel to the long dimension of the cartridge and parallel to the rotational axis of the OPC. With this orientation, a small tab protruding out from a portion of a shutter can slide in a slanted slot that extends at an angle to the OPC axis and at the same angle to the direction of cartridge insertion.
The shutter may be of various types of construction, including generally rigid, generally flexible, or a combination of rigid and flexible. Flexible embodiments may require supporting or guiding structure to space the shutter from the sensitive OPC and to provide for movement of the flexible shutter relative to the OPC without touching the OPC, to help prevent scratching and wear of the OPC.